JP2001195998A - Cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode ray tube which has both suppression effects of the doming quantity and the moire-stripes generation and which can avoid so-called persimmon seed phenomenon. SOLUTION: Projections 23, 24 are formed at opening holes 21, 22 to project from transverse direction ends 21a, 22a into the holes 21, 22. When viewing from a fluorescent substance face, the projecting direction of the projection 23, which is disposed at right of longitudinal center 25 of a shadow mask 20, is directed to a right periphery, and the projecting direction of the projection 24 disposed at left is directed to a left periphery. Accordingly, both suppression effects of the doming quantity and the moire stripes generation are compatible with each other, and there can be avoided so-called persimmon seed phenomenon by which a portion of the beam spot is cut, in the fluorescent substance face of electronic beam.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shadow mask type cathode ray tube used for a television receiver, a computer display and the like.

[0002]

2. Description of the Related Art FIG. 4 is a sectional view showing an example of a conventional color cathode ray tube. The color cathode ray tube 1 shown in FIG. 1 has a substantially rectangular face panel 2 having a phosphor screen surface formed on an inner surface thereof, a funnel 3 connected to the rear of the face panel 2, and a neck portion of the funnel 3. An electron gun 4 built in 3a and a shadow mask 6 provided inside the face panel 2 so as to face the phosphor screen surface 2a.
And a mask frame 7 for fixing this.
In addition, a funnel 3 is used to deflect and scan the electron beam.
A deflection yoke 5 is provided on the outer peripheral surface of the.

[0003] The shadow mask 6 plays a role of color selection for three electron beams emitted from the electron gun 4. A indicates the electron beam trajectory. In the shadow mask, a large number of openings that are electron beam passage holes are formed by etching.

In a color cathode ray tube, an electron beam passage hole is displaced due to thermal expansion caused by an electron beam bombardment, so that an electron beam passing through the electron beam passage hole does not properly hit a predetermined phosphor, and color unevenness occurs. Doing phenomenon occurs. For this reason, a tension (tension) that can absorb the thermal expansion due to the temperature rise of the shadow mask.
Is added in advance, and the shadow mask is stretched and held on the mask frame. According to such a stretch holding, even if the temperature of the shadow mask increases, it is possible to reduce the displacement of the mutual position between the opening of the shadow mask and the phosphor stripe on the phosphor screen surface.

FIG. 5 is a plan view showing an example of a shadow mask. In this drawing, an example of the shadow mask 35 for applying tension mainly in the vertical direction (the screen vertical direction) is shown. The openings 36 are formed at a constant pitch. Each opening 36 indicated by 37
The part between them is called a bridge. The bridge width affects the mechanical strength of the shadow mask, and when the bridge width is reduced, the bridge width is particularly vulnerable to horizontal tension. If the bridge width is increased in order to improve the mechanical strength, the opening area of the opening becomes narrower, so that the luminance characteristics deteriorate.

The vertical pitch of the bridge is also related to the doming amount of the shadow mask. This is because the shadow mask is mainly stretched in the vertical direction, and thermal expansion in the vertical direction is absorbed by the tension, but thermal expansion in the horizontal direction is transmitted laterally by the bridge. Therefore, if the vertical pitch of the bridge is increased, the doming amount can be reduced. In this case, the scanning lines (bright lines) of the electron beams arranged at regular intervals and the electron beam passage holes of the shadow mask are regularly formed. Moire fringes, which are mutual interference fringes with the pattern, are likely to occur, which has been a cause of image quality degradation.

Further, when the vertical pitch of the bridge is increased, there is also a problem that the bridge itself appears to be scattered on the screen. Further, the bridge may be recognized as a stacked pattern (brick-shaped pattern).

Conversely, when the vertical pitch of the bridge is reduced, moire fringes are sufficiently suppressed and the bridge itself is not noticeable, but the doming amount is increased.

On the other hand, for example, as shown in FIG.
A shadow mask 40 in which the vertical pitch of the bridge is small while the vertical pitch of the bridge is small is provided by forming the projections 42a and 42b. Can be suppressed. That is, it is possible to achieve both suppression of the doming amount of the shadow mask, which mainly applies tension in the vertical direction, and suppression of the occurrence of moire fringes.

In a shadow mask having a slot-shaped opening, an opening on the right side of the phosphor screen surface 2a (FIG. 4) with respect to the longitudinal center line of the shadow mask has upper and lower right corners of the opening. In the vicinity, in the opening on the left side of the vertical center line of the shadow mask, near the upper and lower corners on the left side of the opening, a so-called persimmon seed phenomenon occurs in which the obliquely incident electron beam is cut.

FIG. 7A is a cross-sectional view in the horizontal direction near the upper and lower corners of the opening on the right side when viewed from the phosphor screen, with the vertical center line of the shadow mask as a boundary. In this figure, a part of the electron beam light 51 passing through the aperture 50 is
The state cut by the rising shape part 52 of the opening 50 is shown. As described above, when the electron beam is cut near the upper and lower corners on the right side of the aperture, as shown in FIG. 7B, the shape of the beam spot 53, which should have a substantially slot shape, is changed to a persimmon seed. It takes the shape of a shape. Shaded portions 54a, 5
4b corresponds to a portion where the electron beam light has been cut.

Various hole shapes have been proposed in order to prevent persimmon seed phenomena of the electron beam near the upper and lower corners of the hole. For example, Japanese Patent Application Laid-Open No. 1-320738 discloses a shadow mask. In the opening on the right side of the vertical center line of FIG.
(Equivalent to W in (a)) to prevent persimmon seed phenomenon. In Japanese Patent Application Laid-Open No. 63-119139, as shown in FIG. 7C, the upper and lower ends of the opening 55 are widened as shown by a and b to prevent the electron beam from being cut. I have.

[0013]

However, FIG.
In the shadow mask 40 shown in FIG.
With a and 42b, the electron beam can be shielded and the moire fringes can be suppressed as in the case where the bridge vertical pitch is reduced, but there is a problem of the persimmon seed phenomenon as described above. That is, as shown in FIG. 6B, in the opening 41 on the right side of the vertical center line of the shadow mask, the protrusion 4
At the base C of the base 2b, the opening 41 on the left side
The electron beam is cut at the root D of the substrate.

The apertures proposed in Japanese Patent Application Laid-Open Nos. 1-320938 and 63-119139 all attempt to prevent persimmon seed phenomena by the shape of the holes. There is a limit to the response by such a shape.

The present invention solves the above-mentioned conventional problems, and provides a cathode ray tube capable of preventing the so-called persimmon seed phenomenon while suppressing both the amount of doming and the effect of suppressing the occurrence of moiré fringes. The purpose is to provide.

[0016]

In order to achieve the above object, a cathode ray tube according to the present invention is a cathode ray tube provided with a shadow mask having a large number of openings formed in a flat plate, wherein at least the shadow mask is provided. In the opening near the left and right ends of the shadow mask, a protrusion protruding laterally from an end of the opening on the side of the vertical center line of the shadow mask is formed. According to the cathode ray tube as described above, it is possible to prevent the persimmon seed phenomenon in which a part of the beam spot on the phosphor surface of the electron beam is missing while suppressing the doming amount and the effect of suppressing the occurrence of moire fringes.

In the above-mentioned cathode ray tube, it is preferable that an end of the opening farther from the vertical center line has a recess at a position facing a tip of the projecting portion. According to the above-described cathode ray tube, since the concave portion is formed, the protruding portion can be lengthened and the area of the opening can be increased, so that the occurrence of moire fringes and the persimmon can be more reliably achieved. Seed phenomena can be suppressed.

Further, it is preferable that the projecting portion is formed on almost the entire surface of the shadow mask.

It is preferable that the shadow mask is stretched and held in a state where a tensile force is applied in a vertical direction.

Preferably, the shadow mask is formed into a curved surface.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. Each configuration of the color cathode-ray tube described with reference to FIG. 4 is the same in the present embodiment, and a description thereof will be omitted.

FIG. 1 is a perspective view of one embodiment of a color selection electrode. The mask frame 10 is a rectangular frame body, and a pair of elastic members 12 as short-side frames are fixed to a pair of opposing supports 11 as long-side frames. In the shadow mask 13, an opening 14, which is an electron beam passage hole, is formed by etching.

As shown in this figure, a tension system is used, and the shadow mask 13 is stretched and held between the supports 11 while a tensile force is applied mainly in the direction of arrow Y. Although omitted in this drawing, the opening 14 is formed with protrusions as shown by 23 and 24 in FIG.

FIG. 2A is a plan view of one embodiment of the shadow mask. FIG. 2B is an enlarged view of FIG. In the shadow mask 20 shown in this figure, the vertical direction of the figure is the screen vertical direction, the horizontal direction is the screen horizontal direction, and the vertical center line 25 indicates the vertical center line of the shadow mask 20. A region on the right side of the phosphor screen surface 2a (FIG. 4) with respect to the vertical center line 25 (hereinafter, a "right region")
That. ) Are provided in the opening 21.
However, protrusions 24 are respectively formed in the openings 22 arranged on the left side area (hereinafter referred to as “left side area”) when viewed from the phosphor screen surface 2 a with the vertical center line 25 as a boundary. . The openings 21 and 22 adjacent in the vertical direction are connected by a bridge 26.

The projections 23 and 24 are respectively
1, 22 project from one lateral end. Projection 2
3 and 24, the vertical center line 25 in the apertures 21 and 22
From the horizontal direction, i.e., the left and right peripheral directions of the shadow mask. More specifically, the root 23 a of the protrusion 23 in the right region is formed on the end face 21 a of the opening 21 on the vertical center line 25 side. A first opening 27 is formed between the vertically adjacent protrusions 23, and a second opening 28 is provided between a tip 23 b of the protrusion 23 and an end face 21 b of the opening 21. Are formed.

In the left side region, the projecting direction of the projecting portion 24 is opposite to that of the projecting portion 23, and the base portion 24a of the projecting portion 24 is
2 is formed on the end face 22a on the side of the vertical center line 25. A first opening 29 is formed between the vertically adjacent protruding portions 24, and a tip portion 24 b of the protruding portion 24 and the opening 22 are formed.
A second opening 30 is formed between the second opening 30 and the end surface 22b.

Since the projections 23 and 24 are formed, the electron beam can be shielded, so that an effect equivalent to a reduction in the vertical pitch of the bridge 26 is obtained, and the generation of moire fringes is suppressed. I can do it. In addition, the protrusion 2
The openings 3 and 24 do not completely cover the openings 21 and 22 in the lateral direction, but have the second openings 28 and 30 formed therein, so that the tips 23b and 24b and the ends 21b and 2b are not formed.
2b. For this reason, thermal expansion in the lateral direction is not transmitted between the distal end portions 23b and 24b and the end portions 21b and 22b, so that doming can be prevented. That is, according to the present embodiment, it is possible to achieve both suppression of the doming amount of the shadow mask to which tension is mainly applied in the vertical direction and suppression of the occurrence of moire fringes.

A plurality of first openings 27 are formed in one opening 21 in the right region, and each first opening 27 serves as one opening. In other words, it is equivalent to forming a plurality of openings with a reduced vertical pitch in one opening 21.

In this case, a second opening 28 is formed at the upper right and lower right portions of the first opening 27, respectively. Therefore, the right end face 2 of the opening 21 shown in FIG.
The corner portion C as shown in FIG. 6B is not formed in 1b.

That is, the first opening is formed by the second opening 28.
In the vicinity of the upper and lower right corners of the opening 27, the opening is widened, and it is equivalent to forming a plurality of openings in the opening 21 near the upper and lower right corners. .

For this reason, in the region A of the first opening 27, the cutting of the electron beam can be prevented, and the so-called persimmon seed phenomenon in which a part of the beam spot on the phosphor surface of the electron beam is missing is prevented. be able to.

The same is true for the left side region except that the left and right relationship is reversed.
A plurality of openings are formed in one opening 22, and a second opening 30 is formed in an upper left portion and a lower left portion of the first opening 29. Therefore, the left end face 22b of the opening 22 shown in this drawing has a corner portion D as shown in FIG.
Is not formed. Therefore, in the region B of the first opening 29, the electron beam can be prevented from being cut, and the persimmon seed phenomenon can be prevented.

That is, according to the present embodiment, while suppressing both the doming amount of the shadow mask and the suppression of the generation of moiré fringes, the persimmon of which the upper and lower corners on one side of the beam spot on the phosphor surface of the electron beam are chipped is removed. Seed phenomena can be prevented.

Here, the persimmon seed phenomenon as described above is likely to occur in the left and right peripheral portions and corner portions of the shadow mask where the electron beam incident angle becomes large. For this reason, if the openings in which the projections are arranged are formed at least near both the left and right ends as described above, the effect of preventing electron beam cutting can be obtained.

FIG. 3 is an enlarged view of another embodiment of the shadow mask. In the present embodiment, since the depression 32 is formed in the opening 33, the tip 31 a of the projection 31 is formed.
And the electron beam for the width of the phosphor is
Can be reliably shut off. Here, simply increasing the length of the protruding portion without providing a depression narrows the distance between the tip of the protruding portion and the end of the opening, making it difficult to manufacture, which is not appropriate. In the present embodiment, by forming the recessed portion 32, the distance between the tip of the protrusion and the end of the opening can be ensured while the protrusion is lengthened, and manufacturing is not particularly difficult.

Further, since the width of the opening 33 is wider in the portion where the recess 32 is formed than in the other portions, the electron beam is cut at the rising portion of the cross-sectional shape of the opening 33 in the lateral direction. It is not dimmed even if it is done. Therefore, generation of moiré fringes and persimmon seed phenomenon can be suppressed more reliably.

Although the above embodiment has been described on the assumption that the shadow mask is stretched and held, the same effect can be obtained with respect to the above-described prevention of electron beam cutting even when the stretch mask is not held. Is obtained. Therefore,
The present embodiment is also effective for a shadow mask in which a curved surface is formed by press molding and is not stretched and held.

The shape of the projecting portion in the plane direction has been described as an example of a rectangular shape. However, the shape is not limited to this, and the opening and the corner of the projecting portion may be rounded. It is good also as a shape which protrudes gradually toward. As described above, the gradually protruding shape is easily realized by the etching method mainly used in manufacturing the shadow mask,
It is practical.

[0039]

As described above, according to the cathode ray tube of the present invention, in the shadow mask, the projecting portion projecting into the opening is formed, and the projecting direction of the projecting portion is set with respect to the vertical center line of the shadow mask. By setting the direction apart in the horizontal direction, it is possible to prevent the persimmon seed phenomenon in which a part of the beam spot on the phosphor surface of the electron beam is missing, while suppressing the amount of doming and the effect of suppressing the generation of moire fringes at the same time.

[Brief description of the drawings]

FIG. 1 is a perspective view of a color selection electrode according to an embodiment of the present invention.

2A is a plan view of a shadow mask according to an embodiment of the present invention, and FIG. 2B is an enlarged view of FIG. 2A.

FIG. 3 is an enlarged view of a shadow mask according to another embodiment of the present invention.

FIG. 4 is a sectional view of an example of a color cathode ray tube.

FIG. 5 is a plan view of an example of a conventional shadow mask.

6A is a plan view of another example of a conventional shadow mask, and FIG. 6B is an enlarged view of FIG. 6A.

7A is a cross-sectional view of a conventional shadow mask in the horizontal direction near the top and bottom of an aperture. FIG. 7B is a plan view of an example of a conventional beam spot shape. FIG. 7C is a plan view of an example of a conventional aperture shape.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Mask frame 11 Support body 12 Elastic member 13, 20 Shadow mask 21, 22, 33 Opening 26 Bridge 23, 24, 31 Projection 27, 29 First opening 28, 30 Second opening

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Nozomu Arimoto 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Corporation Inside (72) Inventor Hideaki Egasa 1-1, Sachimachi, Takatsuki-shi, Osaka Matsushita Electronics Industrial Co., Ltd. F term (reference) 5C031 EE02 EF05 EF07 EH03 EH04

Claims (5)

[Claims] 1. A cathode ray tube provided with a shadow mask having a large number of openings formed in a flat plate, wherein at least the openings near the left and right ends of the shadow mask have the openings of the shadow mask. A cathode ray tube, wherein a projection protruding laterally from an end on the side of the vertical center line is formed. 2. The cathode ray tube according to claim 1, wherein an end of the aperture farther from the vertical center line has a recess at a position facing a tip of the protrusion. 3. The cathode ray tube according to claim 1, wherein the projecting portion is formed on substantially the entire surface of the shadow mask. 4. The shadow mask is stretched and held while a tensile force is applied in a longitudinal direction.
The cathode ray tube according to any one of the above. 5. The cathode ray tube according to claim 1, wherein the shadow mask is formed into a curved surface.